Researchers at Purdue University have built soft robots using shape-memory alloys (SMAs) woven into fabric. By orienting the alloy threads in different ways and wrapping it around foam blocks, the material can initiate movement.
“Previous works have not combined both flexible sensors and actuators in their designs, usually only addressing one or the other,” explains Michelle Yuen, a doctoral student and one of the primary researchers on the project. This proof-of-concept work — presented at the International Conference on Intelligent Robots and Systems in September — demonstrates that a robot could be made by wrapping this “sensory-active fabric” around a soft body. “We are pushing towards turning anything into a robot simply by wrapping a sheet of fabric around it,” Yuen says.
The researchers programmed their own SMAs to take on the required shapes to bend or contract the foam. They also stitched the alloy threads into the material themselves.”Prior to this work, I had nearly zero experience with sewing, fabrics, needle, thread, etcetera,” Yuen says. “I discovered a whole new world when I started working with fabric-related technology.” Little details, such as thread tension and material, as well as the bias of the fabric, had a significant impact on the end result.
Yuen says a soft robot with locomotion capabilities could one day prove useful for search-and-rescue missions or to navigate “rough, unknown terrain” by moving like an inchworm or a snake. But there is still much work to be done. The Purdue team, which works out of a lab called the Faboratory, hopes to design larger sensory-active fabrics and fabrics with a denser array of sensors. They also hope to achieve more complicated movements, such as multi-access bending, and have better control of the actuation.